Minor refactoring of tdep-i386.c and exceptions.h to fix multiple gcc shadow warnings

[Goncalo Gomes]

The attached patch fixes all the warnings in tdep-i386.c resulting from
enabling shadow warnings in gcc. This is the revised version of  the
patch I sent in yesterday after applying Sergio's comments.

  http://sourceware.org/ml/gdb-patches/2012-08/msg00152.html

-- 
Goncalo <goncalo@promisc.org>
http://promisc.org/